The present invention relates to the interrogating or addressing of a plurality of electrodes by selectively connecting individual ones thereof with a common electrode. Electrodes are so addressed and interrogated in various applications, such as the following: the sequential connection of a plurality of electrodes with associated electrical equipment; the scanning of electrode arrays; the selective addressing of points in coordinate systems defined by electrode sets; and in other similar applications.
Heretofore, it has been known to use brushes made of a suitable electrically conductive material, such as carbon, for selectively connecting individual ones of a plurality of electrodes with a common electrode. Such brushes, however, have a number of serious drawbacks. Firstly, such brushes are subject to excessive wear and thus require costly maintenance or replacement. Secondly, their brushing action inherently generates unwanted noise. Additionally, their brushing action may generate sparks. Consequently, such brushes are unsuitable for use in explosive environments.
Heretofore, electrodes have been addressed by the use of photoconductor materials. One example of a prior art system using photoconductor materials is disclosed in U.S. Pat. No. 3,265,928, issued to Nishino on Aug. 9, 1966. As illustrated by this patent, however, prior art systems and methods for so addressing electrodes are unduly complicated and cumbersome.